Soil and Nutrient Management of Sports Turf
Gordon Johnson Department of Plant and Soil Sciences Oklahoma State University
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Why is Fertilizer Necessary?
Harvest removal of turf nutrients
Turf removal of soil nutrients.
Soil becomes depleted of some nutrients.
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Nutrient Management Challenges?
Can’t see (or otherwise sense) most moderate nutrient deficiencies. When you can see deficiency, turf performance may already have suffered. Nutrient availability is a soil chemical property. Soil test.
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What are the Primary Nutrients Needed by Turf?
Nutrient
Nitrogen (N)
Soil (lb/a)*
400 – 8,000
Turf (lb/a)**
80
Potassium (K)
800 - 60,000
40 12
Phosphorus (P) 400 – 10,000
*Range of total amount in soil. From Chemical Equilibria in Soils. W.L. Lindsay, 1979. Wiley & Sons.
**Calculated for moderate use turf (2 ton/acre dry matter).
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Secondary Nutrients Needed by Turf.
Nutrient
Calcium Magnesium Sulfur
Soil (lb/a)*
14,000 – 1,000,000 1,200 - 12,000 60 – 20,000
Turf (lb/a)**
16 8 6
* Range of total in soil. From Chemical Equilibria in Soils. W.L.Lindsay, 1979. Wiley & Sons. **Calculated for moderate use turf (2 ton/acre dry matter).
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Micronutrients Needed by Turf.
Nutrient
Iron Manganese
Copper
Soil (lb/a)*
14,000 – 1,100,000 40 – 6,000
4 - 200
Turf (lb/a)**
1 0.8
0.08
Zinc Boron Chlorine Molybdenum
20 - 600 4 - 200 40 – 1,800 0.4 - 10
0.6 0.08 4 0.0008
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*Range of total in soils. From Chemical Equilibria in Soils. W.L.Lindsay, 1979. Wiley & Sons. **Calculated for moderate use turf (2 ton/acre dry matter).
Nutrients are Grouped According to Turf Removal.
Primary (N, P, K). Removed in largest amount by turf. Most commonly deficient. Secondary. Removed in moderate amount by turf. Micro. Removed in minute amount by turf.
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Nutrients Not Found Deficient in Oklahoma Turf.
and Magnesium. Liming prevents deficiencies. Manganese. Copper. Zinc.
Calcium
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Nutrients Not Found Deficient in Oklahoma Turf.
Molybdenum. Boron.
Chlorine.
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Nutrients Seldom Found Deficient in Oklahoma.
Sulfur. Iron.
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Sulfur Deficiencies.
Occur
on sandy, low organic matter soils in high rainfall regions with high clipping production and removal of clippings. Soil storage capacity for S is low. Large annual removal of S.
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Sulfur Additions.
Rainfall adds 6 lb/acre/yr of S. Like 120 lb of N (turf needs 1 lb S for every 20 lb N). 2 ½ to 1 lb S/1000 ft /yr adequate. Irrigation. 1.0 ppm S in irrigation water adds 2.7 lb S/acre for each 12” applied. Ammonium Sulfate (21-0-0, 24S).
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Iron Deficiencies.
Limited to high pH soils and specific turf types and cultivars. Turf indigenous to high rainfall, acid soil environments most susceptible. Irrigated in calcareous soils (St. Augustine grass). Iron “Inefficient” cultivars.
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Iron Deficiency in Corn.
Note yellowing (chlorosis) between veins.
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Correcting and Minimizing Iron Deficiency in Turf.
Select tolerant varieties and cultivars. Use a foliar spray of 1 % Fe as ferrous ammonium sulfate (response may be N). May require repeat spraying. Use chelates with caution. Soil apply granular, iron-ammoniumsulfate.
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Review: Nutrients Needed by all Turf, Sometimes Deficient.
Primary
Nitrogen (N)
Secondary
Calcium (Ca)
Micro
Iron (Fe)
Potassium (K) Phosphorus (P)
Magnesium (Mg) Sulfur (S)
Zinc (Zn) Manganese (Mn) Copper (Cu)
= Never Deficient. = Seldom Deficient.
Chlorine (Cl)
Boron (B) Molybdenum (Mo)
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Nutrients Often Deficient in Oklahoma Turf.
(N). Phosphorus (P). Potassium (K).
Nitrogen
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Nitrogen Deficiency.
growth. Mowing. Traffic repair. Light green color. Eventual loss of density.
Reduced
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Bermudagrass Growth Response to Nitrogen.
Growth Rate (lb/1000)
4.1 3.6 3.1 2.6 2.1 1.6 1.1 0.6 0.1 0 1 2 3 4 5 6 7
N Rate (lb/1000)
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Bermudagrass Response to Nitrogen.
1 lb/1000 ½ lb/1000
1 ½ lb/1000
6 lb/1000
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Bermudagrass Color Response to Nitrogen.
12.0
Chlorophyll (mg/g)
11.0 10.0 9.0 8.0 7.0 6.0 5.0 4.0 0 1 2 3 4 5 6 7
N rate (lb/1000)
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Nitrogen Deficiency in Corn.
chlorosis (yellowing) at the tip of the oldest leaf.
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Plant Absorption of Nitrogen by Individual Plants.
Plants absorb Nitrate-Nitrogen from a large volume of soil without competition.
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Plant Absorption of Nitrogen by Individual Plants.
Fertilizer addition removes among-plant competition.
Increased plant density creates competition for N.
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Nitrogen Management.
N
Growth Rate
requirement increase with increasing clipping yield. Plant density. Growth rate.
4.1 3.6 3.1 2.6 2.1 1.6 1.1 0.6 0.1
0
1
2
3
4
5
6
7
N Rate
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Nitrogen Management like Fuel for Engine.
N requirement increases with increasing clipping yield. Plant density. Growth rate.
Fuel requirement increase with increasing work from engine (car). Total miles. Speed (mi/hr).
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Turf-Soil System Relationship (clippings mulched).
Fertilizer-N Nitrate-N
O2
Ammonium-N
Decay
Residue/thatch decay
Soil Organic Matter
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Turf-Soil System Relationship (clippings removed).
Fertilizer-N Nitrate-N
O2
Ammonium-N
Decay
Thatch Decay
Soil Organic Matter
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Turf-Soil System Relationship (clippings removed).
Organic Fertilizer-N Nitrate-N
O2
Ammonium-N Decay Soil Organic Matter
Thatch Decay
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Plant Absorption of Immobile Nutrients (P and K).
Absorption is from just a thin cylinder of soil around each root.
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Immobile Nutrient Absorption at High Plant Density.
•Adequacy of immobile nutrient depends on concentration in soil at root surface. OSU Soil Fertility, 00/02 •Concentration is the same throughout the soil.
Immobile Nutrient Absorption at High Plant Density.
•Little competition among plants for immobile nutrients, even at high intensity management.
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Soil Tests for Immobile Soil Nutrients.
•Soil Test measures concentration throughout the soil (same at root surface). OSU •Must be calibrated to relate soil test value to crop response. Soil Fertility, 00/02
Management of Immobile Soil Nutrients.
Rational
is similar to managing oil for a car or tractor engine. Use calibrated dip-stick.
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Soil Test is like Dip Stick for Engine
Dip Stick. Measures oil level. Not total in crankcase. Critical level=FULL. No benefit from adding more oil.
Soil Test. Measures P Concentration. Not total in soil. Critical level=65. No benefit from adding more P.
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Soil Test Calibration of P and K.
Dip Stick. Fill crankcase so oil gets to all moving parts. Mark level on dipstick “Full”. Drain 1 quart. Mark dipstick “1 qt.” Drain another quart. Mark dipstick “2 qt.”
Soil Test Research. Find soil test level where crop does not respond to P fertilizer. Critical level = 65. Identify soil test where max yield is from: 20 lb. 40 lb. 60 lb.
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Soil Test-P is like Dip Stick for Engine
Dip Stick.
Rec. (add)
None
Soil Test-P (Bermudagrass).
Test
Test
Rec. (add)
None
Full
65
1/2qt.
0-1/2 qt. 1 qt.
40
20 lb/ac
1 qt.
20
40 lb/ac
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Soil Test Calibration of P for Bermudagrass.
Test Index 0
10 20
% Sufficient* P2O5 lb/acre 50
65 80
75
60 40
40 65+
95 100
20 0
*Percentage of growth that could be expected if no fertilizer is applied.
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Soil Test Calibration of K for Bermudagrass.
Test Index % Sufficient K2O lb/acre
0 75 125 200
250+
50 65 80 95
100
140 80 50 30
0
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Effectiveness of Fertilizer-P
•Only about 30 % of P fertilizer is absorbed by turf in year of application. •About 70 % % of P fertilizer reacts with soil to “build up” soil test over time.
P Fertilizer
•Plants absorb P from fertilizer. •Soil adsorbs P from fertilizer.
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Potassium Deficiency.
Common for turf grown in weathered soils developed under high rainfall. More likely for intensive managed turf. Irrigated, clippings removed, central and eastern Oklahoma.
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Potassium Deficiency.
Common
for turf grown in weathered soils developed under high rainfall.
K Usually adequate
K Usually deficient
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Management Strategies.
Correct
acidic soil pH, P and K deficiencies. Soil test for reliable estimate of needs. Soil characteristics change little from year to year.
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Management Strategies.
Control
growth with water and N
inputs. Less control with slow release fertilizers. Cost per lb N ~ 5X. Be skeptical of “Miracle” products.
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